In a modern manufacturing facility, cartons are generally closed automatically by machines. Typically, artisans have custom designed a system of rods for the particular type of closure desired. In designing such a system, the artisan uses his or her judgment as to the length, angular disposition and number of rods required to close the carton. Considering, for instance, the closure of the top major flaps of the carton, a rod might be required to begin closure of the inner major flap from a position generally parallel to the longitudinal axis of the carton and toward the closed position perpendicular to the longitudinal axis of the carton. The first rod might move the flap say 20 degrees toward the closed position, after which a second rod would be positioned to move the flap the next 30 degrees and so forth until the entire 90 degrees or more from the open position to the closed position has been achieved.
The design of appropriate rods has been more a matter of art than science, since it is difficult to create rods with precisely the positions necessary to close the carton flaps smoothly.
Carton flap closures have also been accomplished automatically by means by ploughs or rails which have a particular curvature intended to be suited to closing the flaps of a carton. Unfortunately, here again, design of the ploughs has been empirical in that an artisan must exercise his/her judgment in obtaining a curvature suited to closing the carton at issue.
Powder cartoning equipment from the Italian company ACMA is supplied with cast plow blocks.
Third power polynomial forms for displacement of cams adapted from Gutman, Machine Design, March, 1951 are given in Table 1 on page 8-6 of Marks' Standard Handbook for Mechanical Engineers, 7th Edition, McGraw-Hill, Theodore Baumeister, Editor, the disclosure of which is incorporated by reference herein.
It is important in a manufacturing process that closure of the flaps be continuous and smooth. Any aberrations may cause a stoppage on the line with consequent increase in cost of production. When the rods or ploughs impart anything other than a smooth continuous motion to the flaps, the potential for stoppage of the line exists. For instance, any jerky sudden movements caused by the ploughs or rods may cause a disruption of the packing line.